Air heaters with enclosing dampers for protection against freezing

ABSTRACT

Apparatus for heating outside air having dampers which can be adjusted to fully enclose the heat exchange surfaces to reduce the heating effect without reducing the flow of heat exchange medium. The risk of damage to the coil from freezing is thereby eliminated.

United States Patent Inventor App]. No.

Filed Patented Assignee Clarence L. RIngquIst La Crosse, Wls. 864,002

Oct. 6, 1969 Dec. 14, 1971 The Trane Company La Crosse, Wis.

AIR HEATERS WITH ENCLOSING DAMPERS FOR PROTECTION AGAINST FREEZING 2 Claims, 2 Drawing Figs.

Int. Cl

B60h 1/00 Field of Search [56] References Cited UNITED STATES PATENTS 3,107,724 10/1963 Horn et a1 165/103 3,390,719 7/1968 McCallister 165/103 Primary Examiner-Charles Sukalo Attorneys-Arthur 0. Andersen and Carl M. Lewis ABSTRACT: Apparatus for heating outside air having dampers which can be adjusted to fully enclose the heat exchange surfaces to reduce the heating effect without reducing the flow of heat exchange medium. The risk of damage to the coil from freezing is thereby eliminated.

Patented Dec. 14, 1971 K! I II/ FIG. I

IUI

FIG. 2

64 \INVENTOR.

I CLARENCE L. RINGOUIST ATTORNEY AIR HEATERS WITH ENCLOSING DAMPERS FOR PROTECTION AGAINST FREEZING BACKGROUND OF THE INVENTION With heaters for heating outside air admitted to a building heating system or for heating a mixture of outside air and recirculated air, it has been common practice to modulate the flow of steam or hot water to obtain the desired air temperature. This often results in freezing and extensive damage to the heat exchanger.

SUMMARY OF THE INVENTION In order to prevent damage to heat exchangers] provide dampers to vary the flow of air through the heat exchangers and thus the amount of the air bypassing the heat exchanger to obtain the desired temperature of air. With this control the flow of heat exchange fluid such as steam or hot water can be maintained at a magnitude sufficient to prevent freezing in the heat exchanger.

Other objects and advantages will become apparent as this specification proceeds to describe the invention in detail with reference to the accompanying drawings wherein like elements have been designated by like numerals throughout and in which:

FIG. 1 is a sectional view on a horizontal plane taken on line 1-1 ofFlG. 2;and

FIG. 2 is a vertical sectional view taken on line 2--2 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings numeral designates a conduit connected to receive air or other gas to be heated. The air flowing through duct 10 may be all outside air of a mixture of outside air and building air. The direction of flow of air is indicated by arrows 12.

A heat exchanger 14 has a casing 15 which has flanges 16 secured in fluidtight engagement with flanges 18 on the conduit 10. Heat exchanger 14 has a header 20 for receiving heat exchange fluid such as steam or water from a suitable source such as a boiler not shown.

Heat exhanger 14 also has a return header 22 for returning heat exchange fluid to the boiler or other source.

Heat exchange tubes 24 extend between and conduct heat exchange fluid from header 20 to header 22. A plurality of heat exchange fins 24 are mounted on the tubes 24 in good heat exchange contact therewith.

The heat exchanger as illustrated has three tube and fin bundles 26, 28, and 30. However, it should be understood that there may be more or less bundles. These tube and fin bundles are spaced from each other and from the top and bottom wall of the casing 15 whereby air may flow between the bundles and between the bundles and the sides of casing 15.

Each of the bundles 26, 28, and have upstream walls 32 and downstream walls 34 to permit the flow of air through the bundles only in a direction transverse to the direction of flow 12 through the duct.

Dampers 36 are pivotably mounted at 38 to the upstreamed walls 30 at 40. Dampers 42 are pivotably mounted at 44 to the downstream walls 32 at 46. The dampers 36 and 40 may be provided with sealing strips 48 of flexible material to prevent leakage of air.

Cranks 50 are secured to dampers 36 and cranks 50 are pivotably secured to rods 52 for movement thereby.

Cranks 54 are secured to dampers 40 and cranks 56 are pivotably secured to rods 56 for movement thereby.

Rods 52 and'56 are slidably mounted in the casing 15 and pivotably mounted with respect to an arm 58 which is pivotably mounted at 60 on the casing 15.

A thennostat 62 of the pneumatic type receives air pressure from a source 64 and has a temperature sensing bulb 66 of the averaging type.

If the temperature of air at the bulb 66 tends to exceed the desired temperature the thermostat 62 reduces the pressure transmitted to the an operated damper motor 68 and the damper motor moves the arm 58 in a direction to move the dampers 40 and 26 toward the closed position with respect to the fin and tube bundles 26, 28, and 30.

Although not shown and described, the well-known electrical controls could obviously be used in place thereof.

Although preferred embodiments of my invention have been shown and described, it is contemplated that many changes may be made without departing from the scope or spirit of my invention and I desire to be limited only by the claims.

Iclaim:

1. Gas conditioning apparatus comprising conduit having a first open end for receiving gas to be heated and a second open end for discharging heated gas, a plurality of heat exchangers in said conduit in the path of the flow of gas therethrough, means for conducting a heating fluid through said heat exchangers, said heat exchangers having four sides in the path of flow including substantially closed upstream sides and substantially closed downstream sides, said heat exchangers being spaced from each other and from opposite walls of said conduit for the flow of gas between said heat exchangers and between said heat exchangers and said opposite walls of said conduit, dampers to open and close the other two sides of said heat exchangers to respectively pass the gas through the heat exchangers or to pass the gas between said heat exchangers, said dampers being arranged on both sides of said heat exchangers, means pivotably mounting adjacent dampers on the upstream and downstream sides whereby the gas to be conditioned is passed between the heat exchangers and the walls of the conduit when said dampers are in closing position with respect to the heat exchanger sides and whereby the gas is passed through the heat exchangers when the dampers are pivoted away from the walls of said heat exchangers.

2. The apparatus of claim 1 including thermostatic control means responsive to the temperature downstream of said heat exchangers for controlling said dampers to maintain a substantially constant temperature of gas leaving said heat exchanger.

i t t t t IIIIIHA 

1. Gas conditioning apparatus comprising conduit having a first open end for receiving gas to be heated and a second open end for discharging heated gas, a plurality of heat exchangers in said conduit in the path of the flow of gas therethrough, means for conducting a heating fluid through said heat exchangers, said heat exchangers having four sides in the path of flow including substantially closed upstream sides and substantially closed downstream sides, said heat exchangers being spaced from each other and from opposite walls of said conduit for the flow of gas between said heat exchangers and between said heat exchangers and said opposite walls of said conduit, dampers to open and close the other two sides of said heat exchangers to respectively pass the gas through the heat exchangers or to pass the gas between said heat exchangers, said dampers being arranged on both sides of said heat exchangers, means pivotably mounting adjacent dampers on the upstream and downstream sides whereby the gas to be conditioned is passed between the heat exchangers and the walls of the conduit when said dampers are in closing position with respect to the heat exchanger sides and whereby the gas is passed through the heat exchangers when the dampers are pivoted away from the walls of said heat exchangers.
 2. The apparatus of claim 1 including thermostatic control means responsive to the temperature downstream of said heat exchangers for controlling said dampers to maintain a substantially constant temperature of gas leaving said heat exchanger. 